The Trachea (Human Anatomy): Picture, Function, Conditions, and More Human Anatomy Picture of the Trachea © 2014 WebMD, LLC. All rights reserved. The trachea, commonly known as the windpipe, is a tube about 4 inches long and less than an inch in diameter in most people. The trachea begins just under the larynx (voice box) and runs down behind the breastbone (sternum). The trachea then divides into two smaller tubes called bronchi: one bronchus for each lung. The trachea is composed of about 20 rings of tough cartilage. The back part of each ring is made of muscle and connective tissue. Moist, smooth tissue called mucosa lines the inside of the trachea. The trachea widens and lengthens slightly with each breath in, returning to its resting size with each breath out. Trachea Conditions Tracheal stenosis: Inflammation in the trachea can lead to scarring and narrowing of the windpipe. Surgery or endoscopy may be needed to correct the narrowing (stenosis), if severe.

Tracheoesophageal fistula : An abnormal channel forms to connect the trachea and the esophagus. Passage of swallowed food from the esophagus into the trachea causes serious lung problems. Tracheal foreign body: An object is inhaled (aspirated) and lodges in the trachea or one of its branches. A procedure called bronchoscopy is usually needed to remove a foreign body from the trachea. Tracheal cancer: Cancer of the trachea is quite rare. Symptoms can include coughing or difficulty breathing. Tracheomalacia: The trachea is soft and floppy rather than rigid, usually due to a birth defect. In adults, tracheomalacia is generally caused by injury or by smoking. Tracheal obstruction: A tumor or other growth can compress and narrow the trachea, causing difficulty breathing. A stent or surgery is needed to open the trachea and improve breathing. Trachea Tests Flexible bronchoscopy : An endoscope (flexible tube with a lighted camera on its end) is passed through the nose or mouth into the trachea. Using bronchoscopy, a doctor can examine the trachea and its branches.

Rigid bronchoscopy : A rigid metal tube is introduced through the mouth into the trachea. Rigid bronchoscopy is often more effective than flexible bronchoscopy, but it requires deep anesthesia. Computed tomography ( CT scan ): A CT scanner takes a series of X-rays, and a computer creates detailed images of the trachea and nearby structures. Magnetic resonance imaging ( MRI scan ): An MRI scanner uses radio waves in a magnetic field to create images of the trachea and nearby structures. Chest X-ray : A plain X-ray can tell if the trachea is deviated to either side of the chest. An X-ray might also identify masses or foreign bodies. Larynx Home > Respiratory System > Respiratory System of the Head and Neck > Larynx Larynx The larynx is a tough, flexible segment of the respiratory tract connecting the pharynx to the trachea in the neck. It plays a vital role in the respiratory tract by allowing air to pass through it while keeping food and drink from blocking the airway. The larynx is also the body’s “voice box” as it contains the vocal folds that produce the sounds of speech and singing.

Anatomy The larynx is a short, epithelium-lined tube formed by nine pieces of cartilage and several ligaments that bind them together.... Move up/down/left/right: Click compass arrows Rotate image: Click and drag in any direction, anywhere in the frame Identify objects: Click on them in the image 2D Interactive 3D Rotate & Zoom Change Anatomical System Larynx, Superior (From Above) Full Larynx Description [Continued from above] . . . It is located along the body’s midline in the neck region deep to the skin and the muscles of the neck and anterior to the esophagus and cervical vertebrae. At its superior end, it borders the hyoid bone and the laryngopharynx. The most superior region of the larynx is the epiglottis, a leaf-shaped flap of elastic cartilage covered with epithelium. It connects to the larynx on its tapered inferior end and, except for a brief moment while swallowing, extends its wider superior end slightly into the pharynx just posterior to the tongue. During the process of swallowing, the epiglottis folds over to cover the glottis and prevents food from blocking the airway.

Inferior to the epiglottis is the glottis region of the larynx, which contains the vocal folds. The largest cartilage in the larynx, the thyroid cartilage, supports the glottis. The thyroid cartilage is semicircular in shape with a prominent ridge extending from its anterior surface. This ridge is larger in males than in females and is visible through the skin of the neck, forming the structure known as the Adam’s apple. The thyroid cartilage is connected on its superior surface to the hyoid bone by a wide ligament known as the thyrohyoid membrane. The thyroid cartilage also anchors the anterior ends of the vocal folds, which attach to the inside of the thyroid cartilage at the body’s midline. The cricoid cartilage is the most inferior structure of the larynx and forms the transition between the larynx and the trachea. It is ring-shaped, with its widest portion facing posteriorly and its narrowest portion facing anteriorly.

The cricothyroid ligament connects the cricoid cartilage to the thyroid cartilage along most of its superior surface, while the cricotracheal ligament connects it to the trachea along its inferior surface. The wide posterior of the cricoid cartilage almost touches the thyroid cartilage and forms the cricothyroid joint. Sound pitch is modified by adjustment of the angle of the cricothyroid joint, which helps to control the tension of the vocal folds. Posterior to the thyroid cartilage are three tiny, paired masses of cartilage known as the cuneiform, corniculate, and arytenoid cartilages. The arytenoid cartilages are roughly pyramidal masses of cartilage that sit on top of the posterior side of the cricoid cartilage. These tiny cartilages play a vital role in the production of sound and act as the pivot points for the vocal folds and the muscles that move the vocal folds. Resting on top of the arytenoid cartilages are the horn-shaped corniculate cartilages that help to support the posterior end of the glottis.

The cuneiform cartilages are long, thin bands of cartilage that extend laterally from the corniculate cartilages and support the lateral sides of the glottis. Physiology In the process of swallowing, the larynx plays an important role in the direction of food into the esophagus. The epiglottis normally resides in an upright position just anterior to the lumen of the larynx. In this position, it allows air to pass freely through the larynx during inhalation and exhalation. When food or liquid in the mouth is swallowed, the food pushes the epiglottis posteriorly, flipping its free edge over to cover the glottis and block the swallowed substances from entering the larynx. The food then safely passes on to the esophagus, at which point the epiglottis flips back to its resting position. Occasionally, a person may choke when food gets past the epiglottis or sticks to a structure within the pharynx and blocks the airway. The vocal folds contract to catch the blockage before it passes into the trachea. Coughing pushes air out of the lungs to force the blockage out of the airway.

Sounds are produced in the larynx by the movement of air through the larynx and by the vocal folds, a pair of movable folds in the mucous membrane. The vocal folds are connected to the thyroid cartilage on their anterior ends and the arytenoid cartilages on their posterior end. Air exhaled from the lungs passes through the larynx and vibrates the vocal folds. Several sets of muscles move the arytenoid cartilages and the cricothyroid joint to adjust the position and tension of the vocal folds and thereby control the pitch of sound made by the larynx. Prepared by Tim Taylor, Anatomy and Physiology Instructor SEER Training:Larynx & Trachea Larynx & Trachea Larynx & Trachea Larynx The larynx, commonly called the voice box or glottis, is the passageway for air between the pharynx above and the trachea below. It extends from the fourth to the sixth vertebral levels. The larynx is often divided into three sections: sublarynx, larynx, and supralarynx. It is formed by nine cartilages that are connected to each other by muscles and ligaments.

The larynx plays an essential role in human speech. During sound production, the vocal cords close together and vibrate as air expelled from the lungs passes between them. The false vocal cords have no role in sound production, but help close off the larynx when food is swallowed. The thyroid cartilage is the Adam's apple. The epiglottis acts like a trap door to keep food and other particles from entering the larynx. Trachea The trachea, commonly called the windpipe, is the main airway to the lungs. It divides into the right and left bronchi at the level of the fifth thoracic vertebra, channeling air to the right or left lung. The hyaline cartilage in the tracheal wall provides support and keeps the trachea from collapsing. The posterior soft tissue allows for expansion of the esophagus, which is immediately posterior to the trachea. The mucous membrane that lines the trachea is ciliated pseudostratified columnar epithelium similar to that in the nasal cavity and nasopharynx.

Goblet cells produce mucus that traps airborne particles and microorganisms, and the cilia propel the mucus upward, where it is either swallowed or expelled. Respiratory System | Interactive Anatomy Guide Female Full Respiratory System Description [Continued from above] . . . act as the functional units of the respiratory system by passing oxygen into the body and carbon dioxide out of the body. Finally, the muscles of respiration, including the diaphragm and intercostal muscles, work together to act as a pump, pushing air into and out of the lungs during breathing. Anatomy of the Respiratory System Nose and Nasal Cavity The nose and nasal cavity form the main external opening for the respiratory system and are the first section of the body’s airway—the respiratory tract through which air moves. The nose is a structure of the face made of cartilage, bone, muscle, and skin that supports and protects the anterior portion of the nasal cavity. The nasal cavity is a hollow space within the nose and skull that is lined with hairs and mucus membrane. The function of the nasal cavity is to warm, moisturize, and filter air entering the body before it reaches the lungs.

Hairs and mucus lining the nasal cavity help to trap dust, mold, pollen and other environmental contaminants before they can reach the inner portions of the body. Air exiting the body through the nose returns moisture and heat to the nasal cavity before being exhaled into the environment. Mouth The mouth, also known as the oral cavity , is the secondary external opening for the respiratory tract. Most normal breathing takes place through the nasal cavity, but the oral cavity can be used to supplement or replace the nasal cavity’s functions when needed. Because the pathway of air entering the body from the mouth is shorter than the pathway for air entering from the nose, the mouth does not warm and moisturize the air entering the lungs as well as the nose performs this function. The mouth also lacks the hairs and sticky mucus that filter air passing through the nasal cavity. The one advantage of breathing through the mouth is that its shorter distance and larger diameter allows more air to quickly enter the body. Pharynx The pharynx, also known as the throat, is a muscular funnel that extends from the posterior end of the nasal cavity to the superior end of the esophagus and larynx.

The pharynx is divided into 3 regions: the nasopharynx, oropharynx, and laryngopharynx. The nasopharynx is the superior region of the pharynx found in the posterior of the nasal cavity. Inhaled air from the nasal cavity passes into the nasopharynx and descends through the oropharynx, located in the posterior of the oral cavity. Air inhaled through the oral cavity enters the pharynx at the oropharynx . The inhaled air then descends into the laryngopharynx , where it is diverted into the opening of the larynx by the epiglottis. The epiglottis is a flap of elastic cartilage that acts as a switch between the trachea and the esophagus. Because the pharynx is also used to swallow food, the epiglottis ensures that air passes into the trachea by covering the opening to the esophagus. During the process of swallowing, the epiglottis moves to cover the trachea to ensure that food enters the esophagus and to prevent choking.

Larynx The larynx , also known as the voice box, is a short section of the airway that connects the laryngopharynx and the trachea. The larynx is located in the anterior portion of the neck, just inferior to the hyoid bone and superior to the trachea. Several cartilage structures make up the larynx and give it its structure. The epiglottis is one of the cartilage pieces of the larynx and serves as the cover of the larynx during swallowing. Inferior to the epiglottis is the thyroid cartilage , which is often referred to as the Adam’s apple as it is most commonly enlarged and visible in adult males. The thyroid holds open the anterior end of the larynx and protects the vocal folds. Inferior to the thyroid cartilage is the ring-shaped cricoid cartilage which holds the larynx open and supports its posterior end. In addition to cartilage, the larynx contains special structures known as vocal folds, which allow the body to produce the sounds of speech and singing. The vocal folds are folds of mucous membrane that vibrate to produce vocal sounds.

The tension and vibration speed of the vocal folds can be changed to change the pitch that they produce. Trachea The trachea, or windpipe, is a 5-inch long tube made of C-shaped hyaline cartilage rings lined with pseudostratified ciliated columnar epithelium. The trachea connects the larynx to the bronchi and allows air to pass through the neck and into the thorax. The rings of cartilage making up the trachea allow it to remain open to air at all times. The open end of the cartilage rings faces posteriorly toward the esophagus, allowing the esophagus to expand into the space occupied by the trachea to accommodate masses of food moving through the esophagus. The main function of the trachea is to provide a clear airway for air to enter and exit the lungs. In addition, the epithelium lining the trachea produces mucus that traps dust and other contaminants and prevents it from reaching the lungs. Cilia on the surface of the epithelial cells move the mucus superiorly toward the pharynx where it can be swallowed and digested in the gastrointestinal tract.

Bronchi and Bronchioles At the inferior end of the trachea, the airway splits into left and right branches known as the primary bronchi. The left and right bronchi run into each lung before branching off into smaller secondary bronchi. The secondary bronchi carry air into the lobes of the lungs—2 in the left lung and 3 in the right lung. The secondary bronchi in turn split into many smaller tertiary bronchi within each lobe. The tertiary bronchi split into many smaller bronchioles that spread throughout the lungs. Each bronchiole further splits into many smaller branches less than a millimeter in diameter called terminal bronchioles. Finally, the millions of tiny terminal bronchioles conduct air to the alveoli of the lungs. As the airway splits into the tree-like branches of the bronchi and bronchioles, the structure of the walls of the airway begins to change. The primary bronchi contain many C-shaped cartilage rings that firmly hold the airway open and give the bronchi a cross-sectional shape like a flattened circle or a letter D.

As the bronchi branch into secondary and tertiary bronchi, the cartilage becomes more widely spaced and more smooth muscle and elastin protein is found in the walls. The bronchioles differ from the structure of the bronchi in that they do not contain any cartilage at all. The presence of smooth muscles and elastin allow the smaller bronchi and bronchioles to be more flexible and contractile. The main function of the bronchi and bronchioles is to carry air from the trachea into the lungs. Smooth muscle tissue in their walls helps to regulate airflow into the lungs. When greater volumes of air are required by the body, such as during exercise, the smooth muscle relaxes to dilate the bronchi and bronchioles. The dilated airway provides less resistance to airflow and allows more air to pass into and out of the lungs. The smooth muscle fibers are able to contract during rest to prevent hyperventilation. The bronchi and bronchioles also use the mucus and cilia of their epithelial lining to trap and move dust and other contaminants away from the lungs. Lungs The lungs are a pair of large, spongy organs found in the thorax lateral to the heart and superior to the diaphragm.

Each lung is surrounded by a pleural membrane that provides the lung with space to expand as well as a negative pressure space relative to the body’s exterior. The negative pressure allows the lungs to passively fill with air as they relax. The left and right lungs are slightly different in size and shape due to the heart pointing to the left side of the body. The left lung is therefore slightly smaller than the right lung and is made up of 2 lobes while the right lung has 3 lobes. The interior of the lungs is made up of spongy tissues containing many capillaries and around 30 million tiny sacs known as alveoli . The alveoli are cup-shaped structures found at the end of the terminal bronchioles and surrounded by capillaries. The alveoli are lined with thin simple squamous epithelium that allows air entering the alveoli to exchange its gases with the blood passing through the capillaries. Muscles of Respiration Surrounding the lungs are sets of muscles that are able to cause air to be inhaled or exhaled from the lungs.

The principal muscle of respiration in the human body is the diaphragm, a thin sheet of skeletal muscle that forms the floor of the thorax. When the diaphragm contracts, it moves inferiorly a few inches into the abdominal cavity, expanding the space within the thoracic cavity and pulling air into the lungs. Relaxation of the diaphragm allows air to flow back out the lungs during exhalation. Between the ribs are many small intercostal muscles that assist the diaphragm with expanding and compressing the lungs. These muscles are divided into 2 groups: the internal intercostal muscles and the external intercostal muscles. The internal intercostal muscles are the deeper set of muscles and depress the ribs to compress the thoracic cavity and force air to be exhaled from the lungs. The external intercostals are found superficial to the internal intercostals and function to elevate the ribs, expanding the volume of the thoracic cavity and causing air to be inhaled into the lungs. Physiology of the Respiratory System Pulmonary Ventilation Pulmonary ventilation is the process of moving air into and out of the lungs to facilitate gas exchange. The respiratory system uses both a negative pressure system and the contraction of muscles to achieve pulmonary ventilation.

The negative pressure system of the respiratory system involves the establishment of a negative pressure gradient between the alveoli and the external atmosphere. The pleural membrane seals the lungs and maintains the lungs at a pressure slightly below that of the atmosphere when the lungs are at rest. This results in air following the pressure gradient and passively filling the lungs at rest. As the lungs fill with air, the pressure within the lungs rises until it matches the atmospheric pressure. At this point, more air can be inhaled by the contraction of the diaphragm and the external intercostal muscles, increasing the volume of the thorax and reducing the pressure of the lungs below that of the atmosphere again. To exhale air, the diaphragm and external intercostal muscles relax while the internal intercostal muscles contract to reduce the volume of the thorax and increase the pressure within the thoracic cavity. The pressure gradient is now reversed, resulting in the exhalation of air until the pressures inside the lungs and outside of the body are equal. At this point, the elastic nature of the lungs causes them to recoil back to their resting volume, restoring the negative pressure gradient present during inhalation.

External Respiration External respiration is the exchange of gases between the air filling the alveoli and the blood in the capillaries surrounding the walls of the alveoli. Air entering the lungs from the atmosphere has a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than does the blood in the capillaries. The difference in partial pressures causes the gases to diffuse passively along their pressure gradients from high to low pressure through the simple squamous epithelium lining of the alveoli. The net result of external respiration is the movement of oxygen from the air into the blood and the movement of carbon dioxide from the blood into the air. The oxygen can then be transported to the body’s tissues while carbon dioxide is released into the atmosphere during exhalation. Internal Respiration Internal respiration is the exchange of gases between the blood in capillaries and the tissues of the body. Capillary blood has a higher partial pressure of oxygen and a lower partial pressure of carbon dioxide than the tissues through which it passes. The difference in partial pressures leads to the diffusion of gases along their pressure gradients from high to low pressure through the endothelium lining of the capillaries.

The net result of internal respiration is the diffusion of oxygen into the tissues and the diffusion of carbon dioxide into the blood. Transportation of Gases The 2 major respiratory gases, oxygen and carbon dioxide, are transported through the body in the blood. Blood plasma has the ability to transport some dissolved oxygen and carbon dioxide, but most of the gases transported in the blood are bonded to transport molecules. Hemoglobin is an important transport molecule found in red blood cells that carries almost 99% of the oxygen in the blood. Hemoglobin can also carry a small amount of carbon dioxide from the tissues back to the lungs. However, the vast majority of carbon dioxide is carried in the plasma as bicarbonate ion. When the partial pressure of carbon dioxide is high in the tissues, the enzyme carbonic anhydrase catalyzes a reaction between carbon dioxide and water to form carbonic acid. Carbonic acid then dissociates into hydrogen ion and bicarbonate ion. When the partial pressure of carbon dioxide is low in the lungs, the reactions reverse and carbon dioxide is liberated into the lungs to be exhaled. Homeostatic Control of Respiration Under normal resting conditions, the body maintains a quiet breathing rate and depth called eupnea.

Eupnea is maintained until the body’s demand for oxygen and production of carbon dioxide rises due to greater exertion. Autonomic chemoreceptors in the body monitor the partial pressures of oxygen and carbon dioxide in the blood and send signals to the respiratory center of the brain stem. The respiratory center then adjusts the rate and depth of breathing to return the blood to its normal levels of gas partial pressures. Prepared by Tim Taylor, Anatomy and Physiology Instructor Chapter 21: The esophagus, trachea and main bronchi Chapter 21: The esophagus, trachea and main bronchi Thoracic part of esophagus The esophagus (figs. 21-1 , 21-2 and 21-3 ) has cervical, thoracic, and abdominal parts, extending from the lower end of the pharynx (C6 vertebrae) to the cardiac opening of the stomach (T11 or 12 vertebral level). When a subject is in the erect position, it is about 25 to 30 cm long. The esophagus is a median structure that lies first behind the trachea and then behind the left atrium.

It begins to deviate to the left below the left main bronchus. In the posterior mediastinum it is related to the vertebral column as a string is related to a bow. Hence there is a (retrocardiac) space between it and the vertebrae, which is visible radiographically in oblique and lateral views. The esophagus has constrictions (1) at its commencement, (2) frequently where it is crossed by the left main bronchus, and (3) commonly where it traverses the diaphragm. These are sites where swallowed objects can lodge notwithstanding the fact that the esophagus is distensible and can accommodate almost anything that can be swallowed, e.g., a denture. The impressions of adjacent structures, and their alterations in disease, can be seen radiographically after barium is swallowed (fig. 21-3 ). The esophagus transports food and liquid and can be replaced successfully by a non-muscular tube. The muscular layer is striated above (supplied by the vagi) and smooth below (supplied by parasympathetic, or vagal, and sympathetic fibers). The process of swallowing may be watched fluoroscopically.

A thin barium meal or liquid is "shot down" to the cardiac orifice, whereas a thick meal or a bolus of food travels more slowly. The esophagus is supplied by arteries in the neck (inferior thyroid arteries), thorax (bronchial arteries, direct branches of the aorta, and phrenic arteries), and abdomen (left gastric artery). Veins of the lower part of the esophagus communicate with the left gastric vein, thereby forming an important portal-systemic anastomosis. Portal obstruction (e.g., in the liver with cirrhosis) causes these channels to enlarge, and their varicosities may produce hemorrhage. Pain fibers from the esophagus accompany the sympathetic system. A vague, deep-seated, esophageal pain may be felt behind the sternum or in the epigastrium, and it resembles that arising from the stomach or heart ("heartburn"). In esophagoscopy, measurements are taken from the upper incisor teeth to indicate the beginning of the esophagus (18 cm), the point at which it is crossed by the left bronchus (28 cm), and its termination (43 cm).

Trachea The trachea, or windpipe (figs. 21-1 and 21-2 ), which has cervical and thoracic parts, extends from the inferior end of the larynx (C6 vertebra) to its point of bifurcation (between T5 and 7 vertebral level). It is about 9 to 15 cm in length. The trachea descends anterior to the esophagus, enters the superior mediastinum, and divides into right and left main bronchi. The trachea is a median structure but, near its lower end, deviates slightly to the right, resulting in the left main bronchus crossing anterior to the esophagus. Owing to the translucency of the air within it, the trachea is usually visible above the arch of the aorta in radiographs. The trachea has 15 to 20 C-shaped bars of hyaline cartilage that prevent it from collapsing. Longitudinal elastic fibers enable the trachea to stretch and descend with the roots of the lungs during inspiration. When a subject is in the erect position, the trachea divides between the T5 and T7 vertebral levels.

The carina is the upward-directed ridge seen internally at the bifurcation and is a landmark during bronchoscopy. The arch of the aorta is at first anterior to the trachea and then on its left side immediately superior to the left main bronchus. Other close relations include the brachiocephalic and left common carotid arteries. The trachea is supplied mainly by the inferior thyroid arteries. Its smooth muscle is supplied by parasympathetic and sympathetic fibers, and pain fibers are carried by the vagi. Main bronchi Each main bronchus extends from the tracheal bifurcation to the hilus of the' corresponding lung. The right main bronchus may be considered as having (1) an upper (eparterial) part, from which the segmental bronchi for the upper lobe arise, and (2) a lower part, from which the segmental bronchi for the middle and lower lobes emerge (fig. 21-4 ). The left main bronchus divides into two lobar bronchi, one each for the upper and lower lobes.

The upper lobar bronchus may be considered as having (1) an upper division and (2) a lower, or lingular, division. The right main bronchus, about 2.5 cm in length, is shorter, wider, and more nearly vertical than the left. Because it is in almost a direct line with the trachea, foreign objects traversing the trachea are more likely to enter the right main bronchus. The left main bronchus, 5 cm or more in length, crosses anterior to the esophagus (fig. 21-2 ), which it indents. Both bronchi have cartilaginous rings that are replaced by separated plates at the roots of the lungs. The bronchi are supplied by the bronchial arteries and veins, and their innervation is similar to that of the trachea. Additional reading Terracol, J., and Sweet, R. H., Diseases of the Esophagus, W. B. Saunders Company, Philadelphia, 1958. A general reference with an extensive bibliography. Questions 21-1 What lies anterior to the esophagus in the lower part of the thorax?

21-1 The left atrium lies anterior to the esophagus in the lower part of the thorax. Dilatation of the left atrium can be detected radiographically because of compression of a barium-coated esophagus. 21-2 Where does the trachea divide? 21-2 The trachea divides at the level of thoracic vertebrae 5 to 7 in a subject in the erect position. This would be approximately behind the middle of the body of the sternum. 21-3 How does the right main bronchus differ from the left? 21-3 The right main bronchus is shorter, wider, and more nearly vertical than the left, and it is more likely to receive foreign objects. Figure legends Figure 21-1 The trachea and esophagus in relation to vertebral and sternal levels in a subject in the erect position. Figure 21-2 The relations of the trachea, bronchi, esophagus, and aorta to one another. In the right anterior oblique view, the right lobar and segmental bronchi are omitted because they are not clearly visible in radiographs of this view.

For similar reasons, the left lobar and segmental bronchi are omitted from the left anterior oblique view. The horizontal line indicates the level of the carina. Figure 21-3 Oblique (R.A.O.) view of thorax. The esophagus is shown coated with barium. Note the vertical folds of the mucosa and the indentations produced by the arch of the aorta (upper white arrow) and by the left main bronchus (lower white arrow). Note also the right and left domes of the diaphragm (on the left and right sides of the illustration, respectively) and the fluid level in the stomach (black arrow). (From Bassett, D.L., A Stereoscopic Atlas of Human Anatomy, Sawyer's, Portland, Oregon, 1958. Copyright 1958, Sawyer's Inc.) Figure 21-4 The main, lobar, and segmental bronchi. See also table 22-1 . Jump to: Print Exercise 36: Anatomy of the Respiratory System flashcards | Easy Notecards ARYTENOID CARTILAGES 6.

WHAT IS THE SIGNIFICANCE OF THE FACT THAT THE HUMAN TRACHEA IS REINFORCED WITH CARTILAGINOUS RINGS? REINFORCE THE TRACHEA WALLS TO MAINTAIN ITS OPEN PASSAGEWAY REGUARDLESS OF THE PRESSURE CHANGES THAT OCCUR DURING BREATHING 7. OF THE FACT THAT THE RINGS ARE INCOMPLETE POSTERIORLY? ALLOWS ESOPHAGUS TO EXPAND ANTERIORLY WHEN A LARGE FOOD BOLUS IS SWALLOWED 8. WHAT IS THE FUNCTION OF THE PLEURAL MEMBRANES? PRODUCE LUBRICATING SEROUS FLUID THAT CAUSES THEM TO ADHERE CLOSELY TO ONE ANOTHER, HOLDING THE LUNGS TO THE THORACIC WALL AND ALLOWING THEM TO MOVE EASILY AGAINST ONE ANOTHER DURING THE MOVEMENTS OF BREATHING 9. NAME TWO FUNCTIONS OF THE NASAL CAVITY MUCOSA IT WARMS, MOISTENS - AND - FILTERS THE AIR THAT PASSES THROUGH THE NASAL CAVITY 10.

WHICH MORE COMMONLY TRAPS A FOREIGN OBJECT THAT HAS ENTERED THE RESPIRATORY PASSAGEWAYS? RIGHT MAIN BRONCHUS 14. Ok, so you’re using my notecards which is great. I am glad I could help you out cause I wish I had someone to help me out when I took this course. I know Anatomy is super hard. I only ask that if you find these notecards helpful, you join Easy Notecards and create at least one notecard set to help others out. It can be for any subject or class. Thanks and don’t forget to rate my helpfulness! 15. TRACE A MOLECULE OF OXYGEN FROM THE NOSTRILS TO THE PULMONARY CAPILLARIES OF THE LUNGS NOSTRILS -> NASAL CAVITY -> PHARYNX -> LARYNX -> TRACHEA -?

PRIMARY BRONCHUS -> SECONDARY BRONCHI -> TERTIARY BRONCHI -> BRONCHIOLE -> RESPIRATORY BRONCHIOLE -> ALVEOLAR DUCT ->ALVEOLAR SAC -> ALVEOLAR/CAPILLARY WALLS -> PULMONARY BLOOD 16. 28. WHAT PORTIONS OF THE RESPIRATORY SYSTEM ARE REFERRED TO AS ANATOMICAL DEAD SPACE? WHY? ALL RESPIRATORY PASSAGEWAYS (CONDUCTING ZONE STRUCTURES), BESIDES RESPIRATORY ZONE STRUCTURES, FROM NASAL CAVITY TO TERMINAL BRONCHIOLES. WHY = THEY HAVE NO EXCHANGE FUNCTION 29. DEFINE EXTERNAL RESPIRATION THE GAS EXCHANGE BETWEEN THE BLOOD AND THE AIR-FILLED CHAMBERS OF THE LUNGS (OXYGEN LOADING/CARBON DIOXIDE UNLOADING) 30. EXCHANGE OF GASES BETWEEN SYSTEMIC BLOOD AND TISSUE CELLS (OXYGEN UNLOADING AND CARBON DIOXIDE LOADING) 31.

DEFINE CELLULAR RESPIRATION BODY CELLS REQUIRE AN ABUNDANT AND CONTINUOUS SUPPLY OF OXYGEN. AS THE CELLS USE OXYGEN, THEY RELEASE CARBON DIOXIDE, A WASTE PRODUCT THAT THE BODY MUST GET RID OF. THESE OXYGEN USING CELLULAR PROCESSES ARE REFERRED TO CELLULAR RESPIRATION (CELLULAR METABOLISM) 32. SIU SOM Histology INTRO Nervous Tissue Overview of the Four Basic Tissue Types Epithelial Tissue covers body surfaces (epi, on + thelium, surface). Epithelial tissue consists of cells attached to one another to form an uninterrupted layer of cells that separates the underlying tissues from the outside world. The body's epithelium not only covers its obvious surfaces (such as the epidermis of the skin and the linings of respiratory, urinary, and digestive tracts) but also extends into all of the complex invaginations which form lungs, kidneys, sweat glands, digestive glands, liver, etc. Epithelial tissue provides the essential functions of protection; containment of body fluids; and transport in and out across body surfaces (absorption and secretion).

Embryonically, most epithelial tissues are derived either from ectoderm (e.g., epidermis) or endoderm (e.g., epithelium of trachea and lung). [ More ] [ Examples ] Connective Tissue supports other tissues. Connective tissue consists of several cell types and extracellular products which, together, provide essential functions of mechanical reinforcement, immune surveillance, transport/diffusion of nutrients and wastes, and energy storage (fat). Embryonically, connective tissues derive from mesoderm or mesenchyme. [ More ] [ Examples ] Nervous Tissue is responsible for rapid long-distance signalling, coordination, and "thinking". Nervous tissue consists of highly specialized nerve cells and support cells which are derived from embryonic neuroectoderm and neural crest. [ More ] Muscle Tissue is specialized for gross movement by means of cellular contraction. Embryonically, muscle derives from mesoderm or mesenchyme. [ More ] A note on pathology nomenclature: The names of neoplasms reflect the fundamental nature of their source tissues.

Thus a carcinoma is a cancer of epithelial origin, while a sarcoma is a cancer of mesenchymal (connective tissue or muscle) origin. Parenchyma / Stroma: The parenchyma of an organ consists of that tissue which conducts the specific function of the organ and which usually comprises the bulk of the organ. Stroma is everything else -- connective tissue , blood vessels, nerves, ducts. The parenchyma / stroma distinction provides a convenient way to circumvent the listing of tissue types when discussing an organ. Examples: The parenchyma of the kidney is epithelial tissue (renal tubules and corpuscles). The blood vessels, nerves, and supporting connective tissue of the kidney comprise the stroma. The parenchyma of the spleen is connective tissue (mostly lymphocytes and other blood cells). The supporting fibrous connective tissue of the spleen comprises the stroma. The parenchyma of the heart is muscle tissue (cardiac muscle cells). The nerves, intrinsic blood vessels, and connective tissue of the heart comprise the stroma. The parenchyma of the brain is nervous tissue (nerve cells and glia).

The blood vessels within the brain and the connective tissue associated with these blood vessels are stroma. The parenchyma of the malignant neoplasm is cancer cells. Other tissues, including blood vessels, which grow to support the tumor are stroma. Parenchyma is interesting. Because organ-specific function usually centers on parenchymal cells, histological (and physiological) accounts often emphasize parenchyma. Unfortunately, stroma is commonly ignored as just boring background tissue. Pay attention to the stroma. No organ can function without the mechanical and nutritional support provided by the stroma. If an organ is inflamed, the signs of inflammation appear first in the stroma. (For an example of inflammation from liver , see WebPath .) Historical note: Ignoring inconspicuous tissue features can have consequences. Stromal capillaries are seldom evident in tissue specimens. Nothing calls them to one's attention, so they are often ignored and forgotten. Unfortunately, just such inattention may have delayed for decades the realization that interfering with tumor vasculature might powerfully inhibit tumor growth.

Philosophical note: The concept of "four basic tissue types" provides a simple (and powerful) framework for organizing and learning a great wealth of detail. This concept is more than just a convenient intellectual construct. There is a real boundary layer, the basal lamina (visible microscopically with appropriate stain), which separates tissues of different types. Nevertheless, nature does remind us every so often that her organization is not bound by our simplifying concepts. Although most tissues do correspond closely to one of the four basic tissue types, the usual caveat ("all rules have exceptions") does apply. Exceptions include germ cells, which don't fit the scheme at all, and several specialized varieties of connective tissue which masquerade as epithelium, such as synovial membranes of joint capsules and stria vascularis of the inner ear. Endothelium and mesothelium are special cases, usually classified as epithelial even though they derive from mesenchyme. The best way to appreciate the basic tissue organization of the body is through examples in which this organization is displayed in relatively simple form. Each of the following examples illustrates the distinct difference between epithelial tissue and connective tissue . Click on a thumbnail image for an annotated enlargement.

Skin Fawne Hansen Anatomy Of The Respiratory System The respiratory system (also referred to as the ventilator system) is a complex biological system comprised of several organs that facilitate the inhalation and exhalation of oxygen and carbon dioxide in living organisms (or, in other words, breathing). For all air-breathing vertebrates, respiration is handled by the lungs, but these are far from the only components of the respiratory system. In fact, the system is composed of the following biological structures: nose and nasal cavity, mouth, pharynx, larynx, trachea, bronchi and bronchioles, lungs and the muscles of respiration. (1) A properly functioning respiratory system is a vital part of our good health. Respiratory infections can be acute and sometimes life threatening. They can also be chronic, in which case they place tremendous long term stress on the immune system, endocrine system, HPA axis , and much more. Anatomical Components An image of the respiratory system, showing all the major components, is shown above. 1. Nose and Nasal Cavity The nose and nasal cavity constitute the main external opening of the respiratory system.

They represent the entryway to the respiratory tract – a passage through the body which air uses for travel in order to reach the lungs. The nose is made out of bone, muscle, cartilage and skin, while the nasal cavity is, more or less, hollow space. Although the nose is typically credited as being the main external breathing apparatus, its role is actually to provide support and protection to the nasal cavity. The cavity is lined with mucus membranes and little hairs that can filter the air before it goes into the respiratory tract. They can trap all harmful particles such as dust, mold and pollen and prevent them from reaching any of the internal components. At the same time, the cold outside air is warmed up and moisturized before going through the respiratory tract. During exhalation, the warm air that is eliminated returns the heat and moisture back to the nasal cavity, so this forms a continuous process. 2. Oral cavity The oral cavity, more commonly referred to as the mouth, is the only other external component that is part of the respiratory system.

In truth, it does not perform any additional functions compared to the nasal cavity, but it can supplement the air inhaled through the nose or act as an alternative when breathing through the nasal cavity is not possible or exceedingly difficult. Normally, breathing through nose is preferable to breathing through the mouth. Not only does the mouth not possess the ability to warm and moisturize the air coming in, but it also lacks the hairs and mucus membranes to filter out unwanted contaminants. On the plus side, the pathway leading from the mouth is shorter and the diameter is wider, which means that more air can enter the body at the same speed. 3. Pharynx The pharynx is the next component of the respiratory tract, even though most people refer to it simply as the throat. It resembles a funnel made out of muscles that acts as an intermediary between the nasal cavity and the larynx and esophagus. It is divided into three separate sections: nasopharynx, oropharynx and laryngopharynx. The nasopharynx is the upper region of the structure, which begins at the posterior of the nasal cavity and simply allows air to travel through it and reach the lower sections.

The oropharynx does something similar, except it is located at the posterior of the oral cavity. Once the air reaches the laryngopharynx, something called the epiglottis will divert it to the larynx. The epiglottis is a flap that performs a vital task, by switching access between the esophagus and trachea. This ensures that air will travel through the trachea, but that food which is swallowed and travels through the pharynx is diverted to the esophagus. 4. Larynx The larynx is the next component, but represents only a small section of the respiratory tract that connects the laryngopharynx to the trachea. It is commonly referred to as the voice box, and it is located near the anterior section of the neck, just below the hyoid bone. The aforementioned epiglottis is part of the larynx, as are the thyroid cartilage, the cricoid cartilage and the vocal folds. Both cartilages offer support and protection to other components, such as the vocal folds and the larynx itself.

The thyroid cartilage also goes by a more common name – the Adam’s apple – although, contrary to popular belief, it is present in both men and women. It is typically more pronounced in adult males. The vocal folds are mucous membranes that tense up and vibrate in order to create sound, hence the term voice box. The pitch and volume of these sounds can be controlled by modifying the tension and speed of the vocal folds. 5. Trachea The trachea is a longer section of the respiratory tract, shaped like a tube and approximately 5 inches in length. It has several C-shaped hyaline cartilage rings which are lined with pseudostratified ciliated columnar epithelium. (2) Those rings keep the trachea open for air all the time. They are C-shaped in order to allow the open end to face the esophagus. This allows the esophagus to expand into the area normally occupied by the trachea in order to permit larger chunks of food to pass through. The trachea, more commonly referred to as the windpipe, connects the larynx to the bronchi and also has the role of filtering the air prior to it entering the lungs.

The epithelium which lines the cartilage rings produces mucus which traps harmful particles. The cilia then move the mucus upward towards the pharynx, where it is redirected towards the gastrointestinal tract in order for it to be digested. 6. Bronchi The lower end of the trachea splits the respiratory tract into two branches that are named the primary bronchi. These first run into each of the lungs before further branching off into smaller bronchi. These secondary bronchi continue carrying the air to the lobes of the lungs, then further split into tertiary bronchi. The tertiary bronchi then split into even smaller sections that are spread out throughout the lungs called bronchioles. Each one of these bronchioles continues to split into even smaller parts called terminal bronchioles. At this stage, these tiny bronchioles number in the millions, are less than a millimeter in length, and work to conduct the air to the lungs’ alveoli. The larger bronchi contain C-shaped cartilage rings similar to the ones used in the trachea to keep the airway open. As the bronchi get smaller, so do the rings that become progressively more widely spaced.

The tiny bronchioles do not have any kind of cartilage and instead rely on muscles and elastin. This system creates a tree-like pattern, with smaller branches growing from the bigger ones. At the same time, it also ensures that air from the trachea reaches all the regions of the lungs. Besides simply carrying the air, the bronchi and bronchioles also possess mucus and cilia that further refine the air and get rid of any leftover environmental contaminants. The walls of the bronchi and bronchioles are also lined with muscle tissue, which can control the flow of air going into the lungs. In certain instances, such as during physical activity, the muscles relax and allow more air to go into the lungs. 7. Lungs The lungs are two organs located inside the thorax on the left and right sides. They are surrounded by a membrane that provides them with enough space to expand when they fill up with air. Because the left lung is located lateral to the heart, the organs are not identical: the left lung is smaller and has only 2 lobes while the right lung has 3. Inside, the lungs resemble a sponge made of millions and millions of small sacs that are named alveoli.

These alveoli are found at the ends of terminal bronchioles and are surrounded by capillaries through which blood passes. Thanks to an epithelium layer covering the alveoli, the air that goes inside them is free to exchange gasses with the blood that goes through the capillaries. 8. Muscles of Respiration The last component of the respiratory system is a muscle structure known as the muscles of respiration. These muscles surround the lungs and allow the inhalation and exhalation of air. The main muscle in this system is known as the diaphragm, a thin sheet of muscle that constitutes the bottom of the thorax. It pulls in air into the lungs by contracting several inches with each breath. In addition to the diaphragm, multiple intercostal muscles are located between the ribs and they also help compress and expand the lungs. Physiology of the Respiratory System The respiratory system has a complex physiology and is responsible for multiple functions. There are multiple roles performed by the respiratory system: pulmonary ventilation, external respiration, internal respiration, transportation of gases and homeostatic control of respiration. (3) Here is a brief description of each of those functions.

Pulmonary Ventilation Pulmonary ventilation is the main process by which air flows in and out of the lungs. This is done through the contraction of muscles, as well as through a negative pressure system that is accomplished by the pleural membrane covering the lungs. When the lungs are completely sealed in this membrane, they remain at a pressure that is slightly lower than the pressure of the lungs at rest. As a result of this, the air passively fills the lungs until there is no more pressure difference. At this point, if necessary, additional air can be inhaled by contracting the diaphragm as well as the surrounding intercostal muscles. During exhalation, the muscles relax and this reverses the pressure dynamic, increasing the pressure on the outside of the lungs and forcing air to escape them until both pressures equalize again. Thanks to the elastic nature of the lungs, they revert back to their state at rest and the entire process repeats itself. External Respiration External respiration is a process that allows an exchange of gases to take place between the air located in the alveoli and the blood that is traveling through the capillaries.

This is possible through a difference in pressure between the oxygen and carbon dioxide located in the air, and the oxygen and carbon dioxide in the blood. As a result of this, oxygen from the air is transferred to the blood while carbon dioxide from the blood goes into the air. The useful oxygen is then carried out throughout the body while the carbon dioxide is dispelled through exhalation. Internal Respiration Internal respiration is a similar process except it involves gas exchange between the blood in the capillaries and body tissue. Again, a difference in pressure allows oxygen to leave the blood and enter the tissue while carbon dioxide does the opposite. Transportation of Gases This function of the respiratory system enables oxygen and carbon dioxide to travel throughout the body to wherever they are needed. Most of the gases are carried through blood attached to transport molecules such as hemoglobin, although blood plasma will also have a minimal content of gas. Almost 99% of the entire oxygen found in the human body is transported by hemoglobin. Most of the carbon dioxide is transported from all areas of the body back to the lungs by plasma in the form of bicarbonate ions.

This is created from a catalytic reaction (caused by a carbonic anhydrase enzyme) between water and carbon dioxide, which combine to form carbonic acid. The carbonic acid then splits into hydrogen and bicarbonate ions, with the latter eventually being transformed into carbon dioxide again, taken to the lungs and exhaled. Homeostatic Control of Respiration The last physiological role of the respiratory system is the homeostatic control of respiration or, in other words, the body’s ability to maintain a steady breathing rate. This is termed eupnea. This state should remain constant until the body has a demand for increased oxygen and carbon dioxide levels due to increased exertion, most likely caused by physical activity. When this happens, chemoreceptors will pick up on the increased partial pressure of the oxygen and carbon dioxide and send triggers to the brain. The brain will then signal the respiratory center to make adjustments to the breathing rate and depth in order to face the increased demands. References & Further Reading (2) – InnerBody.com, “Respiratory System”, #full-description . (3) – University of California, San Diego, “Lectures in Respiratory Physiology”, . Are You Suffering From Adrenal Fatigue?

Question: In the human body, what is the 'Trachea more commonly known as?
Answer: The Windpipe